1. Technical Field
The present invention relates generally to digital loop carrier (DLC) systems and, more particularly, to bandwidth management in DLC systems.
2. Description of the Related Art
DLC systems have been an important part of local exchange carrier line deployment for over 15 years. They reduce the copper cabling used in local loops, which comprise the physical connection between a subscriber""s premises and the telecommunications network provider. A DLC system consolidates multiple individual subscriber telephone lines into one or more copper or fiber carrier lines extending from the subscriber area to the network provider central office (CO). DLC systems thereby enable network providers to leverage investments in copper cable in the field by allowing it to transport more subscribers in larger geographic areas.
It has become increasingly important to scale networks to higher speed technologies such as, e.g., digital subscriber line (xDSL) technology, integrated synchronous digital network (ISDN) and other services. These technologies allow data to be transmitted over standard copper cable at speeds of several megabits of data per second. Many factors are driving the need for faster transport capabilities, the most significant of which is increased Internet usage by subscribers.
The resulting increased network traffic has caused bottlenecking in existing DLC systems because of the finite bandwidth capacity of the carrier line infrastructure leading to the CO. A tremendous need thus exists for increasing the capacity and flexibility of existing carrier line infrastructure.
A known method for increasing available bandwidth in existing communication networks comprises compressing all loop traffic (namely, both voice frequency and data) using compression techniques such as adaptive pulse code modulation (ADPCM) and other compression algorithms. While voice signals can generally be compressed without significant degradation, compression has a detrimental effect on the quality and bit rate of data transmission. Consequently, compression techniques are not widely used in loop systems.
A primary object of the invention is to provide a method and apparatus for intelligently managing bandwidth in a DLC system by identifying and selectively compressing signals that can be compressed without significant degradation.
Another object of the invention is to provide a bandwidth management scheme for a DLC system that ensures each new call of getting at least a given default bandwidth when initiated.
An additional object of the invention is to provide a method and apparatus for optimizing bandwidth usage in a DLC system with the surplus bandwidth being made available for broadband transmission and other services.
Yet another object of the invention is to provide a system including central and remote terminals having advanced bandwidth management capability that furnish higher channel capacity in less space, and that are easy to install, use and maintain.
A further object of the invention is to provide a DLC system with a sophisticated bandwidth management scheme that supports multiple telecommunications services, including plain old telephone service (POTS), coin, digital, broadband, ISDN, frame relay, ATM and other services.
Still another object of the invention is to provide a method and apparatus for collecting data on system usage to facilitate network planning and costing.
These and other objects are accomplished by a method and apparatus for managing bandwidth in a DLC system. In a preferred embodiment, the system includes service cards connectable to at least one transport card having a given bandwidth capacity. Each of the service cards supports multiple subscriber channels. Upon initiation of a first call, the system allocates the call to a given time slot of the transport card. The given time slot is assigned a given default bandwidth, e.g., 64 kbps. While the first call is in progress, the system determines whether the call is voice or data (e.g., modem). If the first call is voice, the system may selectively reduce the given default bandwidth allocated to the first call if necessary to ensure that a second call, if initiated while the first call remains in progress, can be assigned the given default bandwidth. Thus, according to the inventive bandwidth management scheme, each new call is ensured of getting at least the default bandwidth when initiated.
The foregoing has outlined some of the more pertinent objects and features of the present invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention as will be described. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the following Detailed Description of the Preferred Embodiment.